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Low vitamin D speeds age-related cognitive decline

On average, older adults with low levels of vitamin D showed much faster decline in episodic memory and executive function.

Older adults with dementia had significantly lower levels of vitamin D compared to those with MCI or normal cognition.

Low vitamin D was more common in African-Americans and Hispanics, compared to whites.

A study involving 382 older adults (average age 75) followed for around five years, has found that those who don’t get enough vitamin D may experience cognitive decline at a much faster rate than people who have adequate vitamin D.

Participants included 17.5% with dementia at the beginning of the study, 32.7% with MCI, and 49.5% cognitively healthy.

Those with dementia had lower levels of vitamin D than the other two groups.

While some people with low vitamin D didn’t show any cognitive decline and some with adequate vitamin D declined quickly, people with low vitamin D on average declined two to three times as fast as those with adequate vitamin D, in two crucial cognitive domains: episodic memory and executive function. Semantic memory and visuospatial ability were not significantly affected.

Factors such as age, gender, education, BMI, season of blood draw, vascular risk, and presence of the 'Alzheimer's gene', ApoE4, were controlled for.

Unlike previous studies of vitamin D and dementia, the participants were racially and ethnically diverse and included whites (41%), African Americans (30%), and Hispanics (25%). Nearly two-thirds (61%) had low vitamin D levels in their blood, including 54% of the whites and 70% of the African-Americans and Hispanics.

Vitamin D is primarily obtained through sun exposure. Accordingly, people with darker skin are more likely to have low levels of vitamin D because melanin blocks ultra-violet rays.

It remains to be seen whether Vitamin D supplements could slow cognitive decline.

A pilot study involving 106 participants of the Rush Memory and Aging Project who had experienced a stroke followed participants for an average of 5.9 years, testing their cognitive function and monitoring their eating habits using food journals.

A small Japanese study has found evidence that those with amnestic mild cognitive impairment (aMCI) show a specific decline in their ability to recognize faces, and this is accompanied by changes in the way they scan faces.

A large study using data from the famous Framingham Heart Study has compared changes in dementia onset over the last three decades. The study found that over time the age of onset has increased while the length of time spent with dementia has decreased.

Data from more than 17,000 healthy people aged 50 and over has revealed that the more regularly participants engaged with word puzzles, the better they performed on tasks assessing attention, reasoning and memory.

Data from over 11,500 participants in the Atherosclerosis Risk in Communities (ARIC) cohort has found evidence that orthostatic hypotension in middle age may increase the risk of cognitive impairment and dementia 20 years later.